Filtration of diesel fuel is well known in the art. The ideal fuel filter provides infinite restriction to the passage of particulates, removal of sediment, removal of water, exhibits zero resistance to fluid flow, and provides unlimited capacity for retaining contaminants. An actual filter cannot exhibit such phenomenal performance and the manufacturer of fuel filters must establish a balance between filter capacity and efficiency.
Conventional filtration of diesel fuel is performed by placing a micro-porous filter membrane between the fuel storage tanks and the fuel injection system wherein the filter traps various impurities. Diesel engines are especially sensitive to impurities and are the prime source of injection system problems. During transportation, transfer, and storage of fuel, impurities can be introduced in a number of ways including condensation. For instance, water combines with other contaminants of diesel fuel and encourages microbiological growth which generates orifice and filter restricting sludge. Contaminated water corrodes and erodes injection nozzles causing spray patterns preventing proper fuel atomization.
In systems where water and fuel pass through high shear pumps, fuel/water interfacial tension is relatively low, and settling time is minimized, fine emulsions may predominate. In systems where water enters before or after low shear pumps, or where there is a prolonged settling time in high interfacial tension fuel, larger water droplets may predominate. In some systems, both fine emulsions and large droplets may be present simultaneously. For these reasons, the primary focus of conventional diesel fuel filtration systems is directed toward the removal of water with an ancillary benefit of removing larger particles.
The more contaminants within the diesel fuel the more prone the fuel injection systems are prone to failure. Current fuel injection systems can operate on commercial available diesel fuel but injection of waste oil into the close tolerances of the injection systems will cause more harm than the aforementioned water induction and literally invites disaster. Waste oils typically have sediment, sulfur, heavy metals such as iron, chromium, lead, copper, tin, aluminum, nickel, silver, manganese, as well as water making the oil suitable only for disposal. These oil contaminants can cause wear, gumming, corrosion, and rust in a fuel system. Combined with water, compounds such as sulfur makes the fuel acidic, which enhances corrosion in fuel injection systems as well as in the engine itself. The chemistry of the waste fuel itself, additives and surfactants, will determine what form the impurity takes.
Unique to the instant invention is the ability to use alternative fuels such as waste oil in a conventional fuel system. The prior art fuel systems include a primary sediment trap for larger particles and a paper filament filter to trap smaller particles and water by separation and/or absorption. In extreme situations a centrifugal pump is used to disperse water in the fuel. The introduction of waste oil into such a prior are fuel system will cause the paper filter and injector to quickly clog. The use of larger paper filters will not remedy the situation as the waste oil will contaminate the paper defeating the filters ability to separate or absorb water.
Therefore, what is lacking in the art is a fuel filtration system that is capable of managing alternative fuels such as lubricating oils, hydraulic oils and the like for their introduction into a conventional fuel system.